| Message ID | 20230511123148.332043-1-aleksandr.mikhalitsyn@canonical.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net-next,v2] sctp: add bpf_bypass_getsockopt proto callback | expand |
Hi, Two things: On Thu, May 11, 2023 at 02:31:48PM +0200, Alexander Mikhalitsyn wrote: > Add bpf_bypass_getsockopt proto callback and filter out > SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS socket options > from running eBPF hook on them. > > These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT > hook returns an error after success of the original handler > sctp_getsockopt(...), userspace will receive an error from getsockopt > syscall and will be not aware that fd was successfully installed into fdtable. > > This patch was born as a result of discussion around a new SCM_PIDFD interface: > https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalitsyn@canonical.com/ Cool, but the description is mentioning the CONNECTX3 sockopt. > > Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks") > Cc: Daniel Borkmann <daniel@iogearbox.net> > Cc: Christian Brauner <brauner@kernel.org> > Cc: Stanislav Fomichev <sdf@google.com> > Cc: Neil Horman <nhorman@tuxdriver.com> > Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> > Cc: Xin Long <lucien.xin@gmail.com> > Cc: linux-sctp@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: netdev@vger.kernel.org > Suggested-by: Stanislav Fomichev <sdf@google.com> > Acked-by: Stanislav Fomichev <sdf@google.com> > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> > --- > net/sctp/socket.c | 31 +++++++++++++++++++++++++++++++ > 1 file changed, 31 insertions(+) > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index cda8c2874691..a211a203003c 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -8281,6 +8281,35 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname, > return retval; > } > > +static bool sctp_bpf_bypass_getsockopt(int level, int optname) > +{ > + if (level == SOL_SCTP) { > + switch (optname) { > + /* > + * These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT > + * hook returns an error after success of the original handler > + * sctp_getsockopt(...), userspace will receive an error from getsockopt > + * syscall and will be not aware that fd was successfully installed into fdtable. > + * > + * Let's prevent bpf cgroup hook from running on them. > + */ This and.. > + case SCTP_SOCKOPT_PEELOFF: > + case SCTP_SOCKOPT_PEELOFF_FLAGS: > + /* > + * As pointed by Marcelo Ricardo Leitner it seems reasonable to skip > + * bpf getsockopt hook for this sockopt too. Because internaly, it > + * triggers connect() and if error will be masked userspace can be confused. > + */ ..this comments can be removed, as they are easily visible on the description later on for who is interested on why such lines were added. Thanks, Marcelo > + case SCTP_SOCKOPT_CONNECTX3: > + return true; > + default: > + return false; > + } > + } > + > + return false; > +} > + > static int sctp_hash(struct sock *sk) > { > /* STUB */ > @@ -9650,6 +9679,7 @@ struct proto sctp_prot = { > .shutdown = sctp_shutdown, > .setsockopt = sctp_setsockopt, > .getsockopt = sctp_getsockopt, > + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, > .sendmsg = sctp_sendmsg, > .recvmsg = sctp_recvmsg, > .bind = sctp_bind, > @@ -9705,6 +9735,7 @@ struct proto sctpv6_prot = { > .shutdown = sctp_shutdown, > .setsockopt = sctp_setsockopt, > .getsockopt = sctp_getsockopt, > + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, > .sendmsg = sctp_sendmsg, > .recvmsg = sctp_recvmsg, > .bind = sctp_bind, > -- > 2.34.1 >
On Thu, May 11, 2023 at 3:12 PM Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> wrote: > > Hi, Hi Marcelo, thanks! Fixed in -v3. Kind regards, Alex > > Two things: > > On Thu, May 11, 2023 at 02:31:48PM +0200, Alexander Mikhalitsyn wrote: > > Add bpf_bypass_getsockopt proto callback and filter out > > SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS socket options > > from running eBPF hook on them. > > > > These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT > > hook returns an error after success of the original handler > > sctp_getsockopt(...), userspace will receive an error from getsockopt > > syscall and will be not aware that fd was successfully installed into fdtable. > > > > This patch was born as a result of discussion around a new SCM_PIDFD interface: > > https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalitsyn@canonical.com/ > > Cool, but the description is mentioning the CONNECTX3 sockopt. > > > > > Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks") > > Cc: Daniel Borkmann <daniel@iogearbox.net> > > Cc: Christian Brauner <brauner@kernel.org> > > Cc: Stanislav Fomichev <sdf@google.com> > > Cc: Neil Horman <nhorman@tuxdriver.com> > > Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> > > Cc: Xin Long <lucien.xin@gmail.com> > > Cc: linux-sctp@vger.kernel.org > > Cc: linux-kernel@vger.kernel.org > > Cc: netdev@vger.kernel.org > > Suggested-by: Stanislav Fomichev <sdf@google.com> > > Acked-by: Stanislav Fomichev <sdf@google.com> > > Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> > > --- > > net/sctp/socket.c | 31 +++++++++++++++++++++++++++++++ > > 1 file changed, 31 insertions(+) > > > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > > index cda8c2874691..a211a203003c 100644 > > --- a/net/sctp/socket.c > > +++ b/net/sctp/socket.c > > @@ -8281,6 +8281,35 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname, > > return retval; > > } > > > > +static bool sctp_bpf_bypass_getsockopt(int level, int optname) > > +{ > > + if (level == SOL_SCTP) { > > + switch (optname) { > > + /* > > + * These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT > > + * hook returns an error after success of the original handler > > + * sctp_getsockopt(...), userspace will receive an error from getsockopt > > + * syscall and will be not aware that fd was successfully installed into fdtable. > > + * > > + * Let's prevent bpf cgroup hook from running on them. > > + */ > > This and.. > > > + case SCTP_SOCKOPT_PEELOFF: > > + case SCTP_SOCKOPT_PEELOFF_FLAGS: > > + /* > > + * As pointed by Marcelo Ricardo Leitner it seems reasonable to skip > > + * bpf getsockopt hook for this sockopt too. Because internaly, it > > + * triggers connect() and if error will be masked userspace can be confused. > > + */ > > ..this comments can be removed, as they are easily visible on the > description later on for who is interested on why such lines were > added. > > Thanks, > Marcelo > > > + case SCTP_SOCKOPT_CONNECTX3: > > + return true; > > + default: > > + return false; > > + } > > + } > > + > > + return false; > > +} > > + > > static int sctp_hash(struct sock *sk) > > { > > /* STUB */ > > @@ -9650,6 +9679,7 @@ struct proto sctp_prot = { > > .shutdown = sctp_shutdown, > > .setsockopt = sctp_setsockopt, > > .getsockopt = sctp_getsockopt, > > + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, > > .sendmsg = sctp_sendmsg, > > .recvmsg = sctp_recvmsg, > > .bind = sctp_bind, > > @@ -9705,6 +9735,7 @@ struct proto sctpv6_prot = { > > .shutdown = sctp_shutdown, > > .setsockopt = sctp_setsockopt, > > .getsockopt = sctp_getsockopt, > > + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, > > .sendmsg = sctp_sendmsg, > > .recvmsg = sctp_recvmsg, > > .bind = sctp_bind, > > -- > > 2.34.1 > >
diff --git a/net/sctp/socket.c b/net/sctp/socket.c index cda8c2874691..a211a203003c 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -8281,6 +8281,35 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname, return retval; } +static bool sctp_bpf_bypass_getsockopt(int level, int optname) +{ + if (level == SOL_SCTP) { + switch (optname) { + /* + * These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT + * hook returns an error after success of the original handler + * sctp_getsockopt(...), userspace will receive an error from getsockopt + * syscall and will be not aware that fd was successfully installed into fdtable. + * + * Let's prevent bpf cgroup hook from running on them. + */ + case SCTP_SOCKOPT_PEELOFF: + case SCTP_SOCKOPT_PEELOFF_FLAGS: + /* + * As pointed by Marcelo Ricardo Leitner it seems reasonable to skip + * bpf getsockopt hook for this sockopt too. Because internaly, it + * triggers connect() and if error will be masked userspace can be confused. + */ + case SCTP_SOCKOPT_CONNECTX3: + return true; + default: + return false; + } + } + + return false; +} + static int sctp_hash(struct sock *sk) { /* STUB */ @@ -9650,6 +9679,7 @@ struct proto sctp_prot = { .shutdown = sctp_shutdown, .setsockopt = sctp_setsockopt, .getsockopt = sctp_getsockopt, + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, .sendmsg = sctp_sendmsg, .recvmsg = sctp_recvmsg, .bind = sctp_bind, @@ -9705,6 +9735,7 @@ struct proto sctpv6_prot = { .shutdown = sctp_shutdown, .setsockopt = sctp_setsockopt, .getsockopt = sctp_getsockopt, + .bpf_bypass_getsockopt = sctp_bpf_bypass_getsockopt, .sendmsg = sctp_sendmsg, .recvmsg = sctp_recvmsg, .bind = sctp_bind,
Add bpf_bypass_getsockopt proto callback and filter out SCTP_SOCKOPT_PEELOFF and SCTP_SOCKOPT_PEELOFF_FLAGS socket options from running eBPF hook on them. These options do fd_install(), and if BPF_CGROUP_RUN_PROG_GETSOCKOPT hook returns an error after success of the original handler sctp_getsockopt(...), userspace will receive an error from getsockopt syscall and will be not aware that fd was successfully installed into fdtable. This patch was born as a result of discussion around a new SCM_PIDFD interface: https://lore.kernel.org/all/20230413133355.350571-3-aleksandr.mikhalitsyn@canonical.com/ Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks") Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Christian Brauner <brauner@kernel.org> Cc: Stanislav Fomichev <sdf@google.com> Cc: Neil Horman <nhorman@tuxdriver.com> Cc: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Cc: Xin Long <lucien.xin@gmail.com> Cc: linux-sctp@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: netdev@vger.kernel.org Suggested-by: Stanislav Fomichev <sdf@google.com> Acked-by: Stanislav Fomichev <sdf@google.com> Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com> --- net/sctp/socket.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+)